Sept 19 (Reuters) - The mysterious 11-day closure of a New Mexico solar observatory stemmed from an FBI investigation of a janitor suspected of using the facility’s wireless internet service to send and receive child pornography, federal court documents showed on Wednesday.

The National Solar Observatory in Sunspot, New Mexico, was evacuated without public explanation on Sept. 6, leading to a swirl of social media speculation and rumors driven by its proximity to two U.S. military installations and the town of Roswell.

Approximately two hours away from the observatory by car, Roswell was the site of a famous 1947 sighting of unidentified flying objects that the U.S. Air Force later said were top-secret high-altitude weather balloons.

UFO conspiracy lore has it that a flying saucer crashed near Roswell, and that remains of the craft and alien crew were clandestinely removed from the crash site by the government and taken to a top-secret test site in Nevada for examination.

But the mystery of the Sunspot Observatory closure proved far less complicated. It was finally explained in newly unsealed FBI records, including a 39-page application for a warrant to search the suspect’s residence.

An agent of the Federal Bureau of Investigation wrote in the affidavit that she was “investigating the activities of an individual who was utilizing the wireless internet service of the National Solar Observatory in Sunspot, New Mexico, to download and distribute child pornography.”

The FBI affidavit identified the suspect as a janitor under contract to clean the facility, whose laptop was found to have been used to connect to the observatory’s wireless system.

According to the affidavit, observatory officials made the decision to close and evacuate the site out of concern that the suspect might pose a danger to other personnel.

The observatory was reopened on Monday.

The person has not been arrested or charged, and no arrest warrant has been issued, according to the FBI.

Frank Fisher, a spokesman for the FBI field office in Albuquerque, told Reuters that the case was still under investigation.

The warrant issued by a U.S. magistrate in Las Cruces, New Mexico, showed that on Sept. 14 agents removed from the man’s home three cell phones, five laptops, one iPad, an external hard drive, 16 thumb drives, 89 compact flash disks and other material. (Reporting by Steve Gorman in Los Angeles; Additional reporting by Joey Roulette in Orlando, Florida)